It's very clear that teams need more track testing time - things like porpoising, bottoming out and real world tire wear isn't something they've been able to model accurately, and the tools for those either don't exist or are so expensive that a small team couldn't buy them anyway.
It's very clear that they don't. Porpoising issues were severe at the beginning of the season, but deminished after just a few races at all teams. Some teams still had issues, but being fair; that included the almighty Mercedes who had a gazillion amount of technicians working on the issue. So it didn't limit itself to the smaller teams. Plus the actual issue of porpoising has proven that teams can solve that without in season testing.
And yes, ofcourse I do understand that with in season testing this likely would have been spotted earlier and also a fix would have been found easier. But this still doesn't justify that in season testing should be brought back just because of this one example.